The World Health Organization on Tuesday acknowledged for the first time that there was “evidence emerging” that the transmission of the coronavirus is airborne, Reuters reported. The WHO’s admission came after 239 scientists wrote it an open letter claiming that the virus can be transmitted through the air.

Benedetta Allegranzi, WHO’s technical lead for infection prevention and control, said at a media briefing in Geneva, Switzerland, on Tuesday that such evidence was emerging, but it was not definitive. “The possibility of airborne transmission in public settings – especially in very specific conditions, crowded, closed, poorly ventilated settings that have been described, cannot be ruled out,” she said. “However, the evidence needs to be gathered and interpreted, and we continue to support this.”

The claim made by the scientists contradicts previous evidence that suggested that it was transmitted from person to person through droplets from the nose or mouth, which are expelled when a person with the disease coughs, sneezes or speaks. The WHO has so far emphasised that the virus can spread through the air only in case of medical procedures that produce aerosols, or droplets smaller than five microns. The global health body has instead promoted frequent hand washing as a means to keep the virus away.

“We have been talking about the possibility of airborne transmission and aerosol transmission as one of the modes of transmission of Covid-19,” Maria Van Kerkhove, technical lead on the pandemic
at the global health body, said at Tuesday’s news briefing. Kerkhove said the WHO will soon publish a scientific paper on the state of knowledge on modes of transmission of the virus.

“A comprehensive package of interventions is required to be able to stop transmission,” Kerkhove said. “This includes not only physical distancing, it includes the use of masks where appropriate in certain settings, specifically where you can’t do physical distancing and especially for healthcare workers.”

Most countries went into complete or partial lockdown when the coronavirus, which originated in China, began to spread earlier this year. If the WHO confirms that the virus can also spread through the air, countries may have to change the public health measures they have adopted to curb the pandemic.

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